I propose to develop a highly innovative patient-specific MRI-based heart modeling environment that represents cardiac functions from molecular processes to electrophysiological and electromechanical interactions at the organ level. I term this environment virtual electrophysiology lab, and propose to translate it into th clinic and apply it to the non-invasive diagnosis and treatment of heart rhythm and contractile disorders in patients with structural heart disease. This pioneering effort offers to integrate, fo the first time, computational modeling of the heart, traditionally a basic-science discipline, withn the milieu of contemporary patient care. The robust and inexpensive non-invasive approaches for individualized arrhythmia risk stratification and guidance of electrophysiological therapies proposed here will lead to optimized therapy delivery and reduction in health care costs, and will have a dramatic personal, medical and economic impact on society. This project seeks to shift the paradigm of cardiac patient care by utilizing the virtual electrophysiology laboratory environment in three applications pertinent to patients with myocardial infarction: 1. Noninvasive prediction of the optimal ablation targets for infarct-related ventricular tachycardia. The vital electrophysiology lab will be used to accurately identify the optimal targets of ablation in each patient heart non-invasively prior to the clinical procedure. Delivery of ablation will then be swit and precise, eradicating all infarct-related ventricular tachycardias with minimum lesion sizes. This will result in a dramatic improvement in the efficacy of and tolerance for the therapy, as wel as in reduction of post-procedure complications. 2. Arrhythmia risk assessment to determine the need for implantable defibrillator deployment. Personalized simulations of arrhythmia inducibility will be used as a noninvasive, inexpensive, and risk-free surrogate for a clinical elect